Carbonyl compounds reactions with selenium-stabilized carbanions

The formation of /3-hydroxyselenides through the reaction of a selenium-stabilized carbanion with carbonyl compounds has been extensively used also in the context of natural product synthesis. The phenylselenoalkyllithium compound 115 was reacted with aldehyde 116 to afford /3-hydroxyselenide 117. In a radical cyclization cascade the tricyclic molecule 118 was generated in good yields and subsequent transformations led to the synthesis of pentalenene 119 (Scheme 28).1 9 Also other natural products like zizaene and khusimone have been synthesized via a similar route.200... 

Selenium-stabilized carbanions can be also generated by 1,4-addition of nucleophilic reagents to a-selanyl a,[3-unsaturated carbonyl compounds. The conjugate addition of trialkylsilyllithium compounds to 133, followed by reaction with allyl iodide, afforded the addition products 134 with good m-stereoselectivity (R = Me dr 86 14 R = Ph dr 94 6) (Scheme 34).214 The addition of lithium dialkylcuprates to 2-phenylselanylcycloalk-2-enones has also been used for the synthesis of natural products.215,216... 

The formation of -hydroxy selenides through reaction of a selenium-stabilized carbanion with a carbonyl compound has been extensively used, in particular for the synthesis of natural products [1 - 4, 33]. The most recent... 

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